CHEM 1210 Lecture Notes - Lecture 7: Chemical Kinetics, Activation Energy, Covalent Bond

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3 Apr 2018

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Reaction for combustion of gasoline to drive cars: Rate = (change in concentration) / (change in time) Chemical kinetics: the study of the rates of chemical reactions (mol/l/min) The rates of chemical reactions are affected by the following factors: In order for two species, a and b (they may be molecules or ions), to react, they must collide. The conclusion is that most collisions do not result in a reaction. A collision that results in a reaction is called an effective collision. It is possible to calculate how many collisions will take place between a and b in a given period of time. Such calculations indicate that the rate at which a and b collide is far greater than the rate at which they react. There are two main reasons why some collisions are effective and others are not. Activation energy: the minimum energy required for a reaction to take place.

Related Questions

Theoretical Models for Chemical Kinetics and Reaction Profiles

Chemical reactions involve the making and breaking of chemical bonds. Since different types of bonds have different bond strengths, the energy of the reacting system changes as the reaction progresses. A graph that shows the change in energy as a function of the progress of the reaction is known as a reaction profile.

According to the theories of chemical reactions, when molecules collide in the correct orientation with a sufficient amount of energy, an activated complex or transition state is formed. The reaction then proceeds and the activated complex decomposes into products.

Part A

Observe the following reactants and predict which of the following may form the potential products given the values for the energy of activation, Ea, and enthalpy of the reaction, ÎH, in combination with the molecular orientation.

Check all that apply.

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Part B

The progress of a reaction is determined by various steps involving energy changes with respect to collision theory. Identify the key features of the reaction profile below.

Drag the appropriate labels to their respective targets in the energy profile diagram.

Did the reaction actually stop when the blue-black color appeared? Explain briefly

EXPERIMENT 16 A Kinetic Study of an Iodine Clock Reaction OBJECTIVES: To measure experimental reaction rates under different conditions. To use the method of initial rates to determine the order of reaction. To determine the rate constant of a reaction at different temperatures. To determine the activation energy of a reaction using graphical techniques. rate law. To make deductions regarding a reaction mechanism, based on the INTRODUCTION: According to chemical kinetics, it is possible to write down a Rate Law' for any chemical equation: Rate k[A]m [B] This rate law can be used to calculate the rate at which that particular reaction will proceed when a given concentration' of [A] and [B] are present in the system. However, to do this we must know the value of (it is temperature dependent). k rate constant m order with respect to concentration of A. n order with respect to concentration of B. It is important to realize that the values of k, m and n cannot be determined by looking at the chemical equation. They must be deduced experimentally someone must actually run and time the reaction under varying conditions. In this lab, we will studythe Rate Law forthe following reaction between the persulfate ion,s2os and the iodide ion. General Rate Lane. Rate -k ]m [s20g2-1n This reaction is called a clock reaction b of the thiosulfatestarch indicator system we use to time the reaction. Every you run this reaction, your flask will contain an indicator system consisting of time 5.0 x 105 moles of thiosulfate' ions, S2032, and a little starch. When the two reactants, Ose are first mixed start the reaction, every molecule of I2 that is produced reacts immediately with any nt according to the following chemical equation. S2032-preset 21- S40 12 2 S203 This removes the first 2,5 x 10 s moles I2 (look at stoichiometry of reactions above) from the system but then the thiosulfate is gone. This point is marked by the almost instantaneous appearance of an intense blue-black Also called Rate Equation and Rate Law Expression square brackets around anything, [X], means moles per liter of Xor molarin of x. You pipet 100 ml of 0.0050 M Naasio, into each flask.

CHEM 1210 Lecture Notes - Lecture 7: Chemical Kinetics, Activation Energy, Covalent Bond

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